1. Field
Example embodiments relate to hybrid resistive memory devices, and more particularly, to hybrid resistive memory devices including two or more resistive memory devices which are serially connected, and methods of operating and manufacturing the same.
2. Description of the Related Art
The brain of an animal receives lots of information, processes the information, gives a command to each body part, and sustains life. A cerebral cortex, which surrounds a surface of a cerebral hemisphere, plays a key role in receiving information, making determinations, and giving commands. The cerebral cortex includes a plurality of nerve cells called neurons, which include a plurality of projections. Each of the neurons includes a cell body, an axon, and dendrites. The axon contacts another nerve cell and sends information, and the dendrites receive signals.
At a synapse, an end of an axon of one neuron comes into close apposition with dendrites of a next neuron. Information storage and signal transmission occur due to a change in weight in the synapse by two plasticities (short-term plasticity and long-term plasticity). When the short-term plasticity occurs, the weight of the synapse is increased for a short period of time and rapidly returns to its initial state. If the synapse is continuously stimulated and the long-term plasticity occurs, the synapse is permanently changed. The long-term plasticity may occur more effectively with a smaller number of stimulations at shorter intervals than the short-term plasticity. Although the neuron has such an effective information processing mechanism, it is said to be difficult to simulate such plasticities of the neuron by using software because of a complicated process of the brain.